The polyols used in the polyurethane production industry are generally derived from petroleum, but currently there is a trend to use renewable sources such as vegetable oils for production of polyols based on these oils.
The production of polyols from of vegetable oils has been described in several documents in the state of the art:
Patent Application U.S. 20070232816 reveals a process for the production of a polyol monomer which consists of reacting an unsaturated acid fatty or its corresponding triglycerides with a polyhydric alcohol in the presence of a catalyst and an emulsifier in order to prepare a monoglyceride. Said process also comprises an epoxidation stage of the unsaturated fatty acids of said monoglyceride, and a reaction stage of the epoxidized monoglyceride with a polyhydric alcohol.
Publication W0/2006/012344 provides methods for the preparation of unsaturated polyols based one modified vegetable oils, as well as methods for the production of oligomeric polyols based on modified vegetable oils. This publication shows a method of manufacturing an oligomeric polyol based on a modified vegetable oil, where a mixture is made to react that comprises an epoxidized oil vegetable and a compound that allows the opening of the ring for form an oligomeric polyol based on the modified vegetable oil, where the oligomeric polyol based on the modified vegetable oil comprises at least 20% of oligomers and has a viscosity at 25° C. less than approximately 8 Pa s.
Publication W0/2009/058367, as well as Publication W0/2009/058368 refer to methods for obtaining a polyester polyol from natural oils. Such methods comprise the stage of reacting the monohydric fatty acids to the esters with a multifunctional reagent initiator to form the polyester polyol. This document reveals a process where a methanolysis of oils (Sunflower, Soya, Canola) is performed followed by an epoxidation process.
U.S. Pat. No. 6,433,121 reveals a method for the production of polyols based on natural oils through the use of a two consecutive-stage process involving epoxidation and hydroxylation. This document mentions in a general manner that palm oil may be used; however, without limitation, the preferred realization of the invention corresponds to the use of soybean oil.
Publication W0/2009/058368 reveals methods for the obtaining a polyester polyol from natural oils. Said method comprises a stage of reacting the hydroxylated fatty acids to the esters with a reagent multifunctional initiator to form polyester polyol. The process revealed in this document performs a methanolysis of oils (Sunflower, Soya, Canola) followed by a process of epoxidation. Additionally, the document mentions in a general way that palm oil could be employed in the process.
In the research published in the Article by G. Ruiz Aviles, “Obtaining and characterizing of a biodegradable polymer from Cassava starch,” Engineering and Science, Medellin, 2006, a biodegradable polymer is obtained from yucca starch by processing modified starch mixtures with glycerin and water as plasticizers, using an open mill and a single extruder spindle. The variables to control during the extrusion are: temperature, torque and spindle rotation speed profile. The polymer obtained has applications in food packaging and for garbage bags.
On the other hand, the article by H. Yeganeh, P. et al., “Preparation and properties of novel biodegradable polyurethane networks based on castor oil and poly(ethylene glycol),” Polymer Degradation and Stability 92, Iran, 2007, reveals a method of preparation of polyurethane with polyols obtained from castor oil and mixtures with polyethylene glycol that were synthesized through the reaction of the prepolymer with 1,6 hexamethylene diisocyanate. The polymer obtained has a rate of biodegradability compatible for be used in biomedical applications.
The article by S. Ahmad, Md, et al., “Urethane modified boron filled polyesteramide: a novel anti-microbial polymer from a sustainable resource,” European Polymer Journal, 2004 describes a procedure for obtaining an antimicrobial polymer from soybean oil; the polymer is composed of polyesteramide filled with boron that is polymerized for form a polyester amide urethane. The material obtained was evaluated for antimicrobial and antifungal activity, verifying that the different compositions inhibit microbial growth.
Another article, by V. Sharma, et al., “Addition polymers from natural oils: A review,” Prog Polym. Sci. 31, India, summarizes the theoretical aspects of the production of polymers from renewable sources, especially from vegetable oils, showing the differences in the structure of each oil and its influence on the polymer properties. It poses various alternatives for natural oils such as soy, corn, tung, linseed, castor oil plant and fish oil for the production of polymer materials.
Finally, the article by G. Gunduzb, et al., “Water-borne and air-drying oil-based resins,” Progress in Organic Coatings 49, Turkey 2003, presents a procedure for the preparation of polyurethane dispersed in water for application as a varnish. The resin is produced for the preparing a maleinised monoglyceride, TDI as isocyanate, silicone, and ethylene diamine. Sunflower oil was used for this development as a renewable resource to produce the monoglycerides.
Palm oil is the second most cultivated vegetable oil in the world following soybean oil. Ninety percent of palm oil produced is exported from Malaysia and Indonesia. Palm oil is derived from the fruits clusters of the palm, is semisolid at environmental temperature due to the combination of triglycerides of high and low fusion points, and has a red-orange color due to its high content of carotenes. It is composed mainly of fatty acids, the amounts typical of these acids being: 45% palmitic, 40% oleic, 10% linoleic and 5% stearic. Thanks to its good resistance to oxidation and to heating at high temperatures, palm oil is employed in diverse industries for its good performance and economy. In energetic terms palm oil requires less energy than others oils for the production of one ton, such as soy and rapeseed oils.
Initially palm oil production was only used for human consumption, but in view of the overproduction of palm oil of in Malaysia, Thailand and Indonesia, the need to search for alternative uses for the oil has been identified. Some different areas of knowledge have been identified for its use, such as medicine, agriculture development of new materials, civil works, and biofuels, among others.
The production of polyols to from of palm oil, specifically oligomeric polyols, has been described in Publication W0/2007/123637, which discloses oligomeric polyols obtained from palm oil and compositions that comprise these polyols, as well as a process for obtaining an oligomeric polyol based on modified palm oil, which comprises providing an epoxidized composition based on palm oil and making it react with a compound that allows the opening of the ring to form an oligomeric polyol where the oligomeric polyol based on the modified palm oil comprises at least 40% oligomers by weight, has a hydroxyl number of around of 65 mg KOH/g sample or less, an average number of hydroxyl functionality of 2.5 or less, and viscosity at 25° C. of less than approximately 4 Pa s.
While the prior art has searched for solutions to the technical problem, which is to provide methods for obtaining “green” polyols, that is, from vegetable oils which include palm oil, as well as obtaining polyurethane foams from of these “green” polyols with properties that allow their application in the different uses mentioned above, none of the documents of the prior art refers to a procedure for obtaining polyols derived from palm for the preparation of polyurethane, in which two methods of preparation are combined to grant a higher functional ty to the final molecular structure. This improves the characteristics of the polyurethane obtained from said polyol, conferring properties such as greater functionality and greater crosslinking.
Although in other inventions polyols have been obtained from vegetable oils, the products prepared from such polyols are brittle due to the concentration of hydroxyl groups at only one end of the carbon chain.
Additionally and in relation to the conditions of operation of the glycerolysis method, the present invention achieved decreasing the reaction temperature for obtaining a polyol with favorable results regarding the decrease in energy costs.
The present invention provides a simple method for its realization, is not expensive, and gives the end result of a product with high technical and functional qualities that places it above those of conventional type and within the same line found in the prior art, with the advantage of having in its raw materials a polyol from renewable natural sources.
The present invention produces polyols with molecular weights between 314 and 3366 and with a hydroxyl number of between 50 and 450 mg KOH/g sample.
The resulting rigid foams were tested for the density (according to STM C373-88) with results between 0.284 and 0.658 g/cm3, Young module (according to ASTM 0695-10) with results between 8.94522 and 54.92330 MPa, and maximum effort (according to ASTM 0695-10) with results between 0.92037 and 8.29101 MPa.
The resulting semi-rigid foams were tested for density (according to ASTM C373-88) with results between 0.129 and 0.158 g/cm3, Young module (according to ASTM 0695-10) with results between 0.78727 and 1.54311 MPa, and maximum effort (according to ASTM 0695-10) with results between 0.07012 and 0.09753 MPa.